JP6672748B2 - Control device, machine tool, control method, and computer program - Google Patents

Description

  The present invention relates to a control device, a machine tool, a control method, and a computer program for controlling movement of a spindle on which a tool is mounted.

  The machine tool includes a control device that controls movement of a spindle on which a tool is mounted. The control device sets a plurality of command points indicating the position of the spindle, and sets a machining path. When the tool mounted on the spindle forms a three-dimensional curved surface on the work, the control device calculates and generates a plurality of curves in which minute line segments between the command points are continuous.

  For example, a plurality of curves are generated on a plane (horizontal plane) parallel to the front-back direction and the left-right direction. The plurality of curves are arranged in the front-back direction or the left-right direction. The control device sets a vertical position on each curve. In addition, the control device interpolates the generated curve based on a smooth curve such as a spline curve or a Bezier curve because a sharp portion appears at the joint of the minute line segments. At each of the set upper and lower positions, the spindle moves along the interpolated curve to process the workpiece (for example, see Patent Document 1).

Japanese Patent No. 3466111

  However, even when the above-described interpolation is performed, a scale-like pattern appears on the work surface due to a difference between inclinations of adjacent curves, a quantization error generated by a calculation in the control device, and the like. Patent Literature 1 inserts a command point so as to form a smooth line between the command points without correcting the command points. Therefore, although the command point itself is incorrect, the command point passes through the command point, and there is a problem that a scaly pattern appears on the work surface described above.

  The present invention has been made in view of such circumstances, and has as its object to provide a control device, a machine tool, a control method, and a computer program capable of forming a smooth curved surface on a work.

  A control device according to the present invention is a control device that sets a machining path based on a plurality of command points indicating a position of a spindle, and controls movement of the spindle based on the machining path, wherein the machining path is annular. An evaluation section setting unit that sets an evaluation section so as to be perpendicular to the processing path; an operation unit that calculates an intersection of the evaluation section set by the evaluation section setting unit and the processing path; An intersection position correction unit that corrects the position of the intersection calculated by the unit, and a command point position correction unit that corrects the position of the command point in a direction intersecting the machining path based on the intersection corrected by the intersection position correction unit. And characterized in that:

  The control device according to the present invention is characterized in that the machining path has a first path part having an annular shape and a second path part located inside the first path part and having an annular shape. Sets a first reference point setting unit that sets a first reference point on the first path unit; and sets a second reference point at a position on the second path unit that is closest to the first reference point. A second reference point setting unit for calculating the evaluation cross section based on the first reference point and the second reference point.

  In the control device according to the aspect of the invention, the processing path includes a plurality of path sections including the first path section and the second path section, and the first path section is located at an outermost position in the plurality of path sections. The second path section is located at the innermost side of the plurality of path sections.

  The control device according to the present invention, wherein the machining path has a spiral shape, the plurality of command points include a start point command point located at a start point of the machining path and an end point command point located at an end point of the machining path, A starting point side path portion setting section that sets one of the first path section or the second path section between the first command point and the first command point different from the start point command point; and the end point command point. An end point side path section setting section that sets the other of the first path section and the second path section between the second command point and the second command point different from the end point command point.

  A machine tool according to the present invention includes any one of the control devices described above and the spindle.

  The control method according to the present invention is a control method for setting a machining path based on a plurality of command points indicating a position of a spindle, and controlling movement of the spindle based on the machining path, wherein the machining path is annular. The evaluation section is set so as to be perpendicular to the machining path, the intersection of the set evaluation section and the machining path is calculated, the position of the calculated intersection is corrected, and based on the corrected intersection, The position of the command point in a direction intersecting the machining path is corrected.

  The computer program according to the present invention can be executed by a control device that sets a machining path based on a plurality of command points indicating the position of the spindle according to the machining program and controls the movement of the spindle based on the machining path. A computer program, wherein the machining path has an annular shape, and the control device sets an evaluation section to be perpendicular to the machining path, an evaluation section setting unit, and an evaluation set by the evaluation section setting unit. A computing unit that computes an intersection of the cross section and the machining path, an intersection position modifying unit that corrects the position of the intersection computed by the computing unit, and an intersection that is modified by the intersection position modifying unit. It is characterized by functioning as a command point position correction unit for correcting the position of the command point in the direction.

  In the present invention, the evaluation section is set so as to be perpendicular to the annular processing path, the position of the intersection of the evaluation section and the processing path is corrected, and based on the corrected position of the intersection, the evaluation section intersects with the processing path. Correct the position of the command point in the direction of

  In the present invention, a first reference point and a second reference point are set in the first path portion on the outer peripheral side and the second path portion on the inner peripheral side, respectively. The second reference point is located closest to the first reference point. By setting the evaluation section so that the first reference point and the second reference point are located on the evaluation section, the evaluation section becomes substantially perpendicular to the machining path.

  In the present invention, since the first path portion is located on the outermost peripheral side and the second path portion is located on the innermost peripheral side, it is possible to prevent the evaluation cross sections from intersecting with each other.

  In the present invention, one of the first path portion and the second path portion is located on the starting point side of the machining path, and the other is located on the end point side of the machining path. When the starting point is located at the center of the spiral machining path, the first path section is located on the end point side, and the second path section is located on the starting point side. When the end point is located at the center of the machining path, the second path section is located on the end point side, and the first path section is located on the start point side.

  In the control device, the machine tool, the control method, and the computer program according to the present invention, the evaluation section is set to be perpendicular to the annular processing path, and the position of the intersection of the evaluation section and the processing path is corrected. And correcting the position of the command point in the direction intersecting the machining path based on the corrected position of the intersection. When a plurality of evaluation sections are set so as to extend radially from the center of the processing path with respect to the annular processing path, there are portions where the density of the evaluation section is high and low, and the correction accuracy for the command point is reduced. May be. In the present invention, by making the evaluation section perpendicular to the machining path, even if a difference occurs in the density of the evaluation section, it is possible to prevent a decrease in correction accuracy for the command point.

FIG. 2 is a perspective view schematically showing a machine tool. FIG. 2 is a block diagram schematically illustrating a configuration of a control device. FIG. 3 is a plan view schematically showing a processing path and an evaluation cross section for a work. It is a perspective view which briefly shows the evaluation cross section with respect to a workpiece. 5 is a flowchart illustrating a processing path setting process performed by a control device. It is a flowchart explaining the outermost / innermost calculation processing. It is a schematic diagram which roughly shows the machining path | route of the main shaft which moves from an outer peripheral side to an inner peripheral side in a spiral shape. It is a schematic diagram which roughly shows the machining path | route of the main shaft which moves from an inner peripheral side to an outer peripheral side in a spiral shape. It is a flowchart explaining an evaluation cross section setting process. It is a schematic diagram explaining an evaluation cross section setting process. FIG. 4 is a schematic diagram schematically showing a command point, an intersection of an evaluation section and a machining path. It is a conceptual diagram showing an example of an intersection table. FIG. 9 is an explanatory diagram illustrating a first correction method of an intersection point on an evaluation section. FIG. 9 is an explanatory diagram illustrating a second method of correcting the intersection point on the evaluation section. FIG. 9 is an explanatory diagram illustrating a method of correcting a command point. It is a flowchart explaining a command point position correction process.

  Hereinafter, the present invention will be described with reference to the drawings showing a machine tool according to an embodiment. In the following description, upper and lower, right and left, and front and rear indicated by arrows in the drawings will be used. FIG. 1 is a perspective view schematically showing a machine tool.

  The machine tool 100 includes a rectangular base 1 extending forward and backward. A work holding part 3 for holding a work is provided on the front side of the upper portion of the base 1. The work holding unit 3 is rotatable around an A-axis whose axial direction is the horizontal direction and a C-axis whose axial direction is the vertical direction.

  A support 2 for supporting a column 4 described later is provided on the rear side of the upper portion of the base 1. A Y-axis direction moving mechanism 10 that moves the moving plate 16 in the front-rear direction is provided above the support base 2. The Y-axis direction moving mechanism 10 includes two rails 11 extending forward and backward, a Y-axis screw shaft 12, a Y-axis motor 13, and a bearing 14.

  The rails 11 are provided on the left and right of the upper portion of the support 2. The Y-axis screw shaft 12 extends back and forth and is provided between the two rails 11. A bearing 14 is provided at each of a front end portion and an intermediate portion of the Y-axis screw shaft 12. The illustration of the bearing provided in the middle part is omitted. The Y-axis motor 13 is connected to the rear end of the Y-axis screw shaft 12.

  A nut (not shown) is screwed to the Y-axis screw shaft 12 via a rolling element (not shown). The rolling element is, for example, a ball. A plurality of sliders 15 are slidably provided on each rail 11. The moving plate 16 is connected to the upper part of the nut and the slider 15. The moving plate 16 extends in the horizontal direction. The rotation of the Y-axis motor 13 rotates the Y-axis screw shaft 12, the nut moves in the front-back direction, and the moving plate 16 moves in the front-back direction.

  An X-axis direction moving mechanism 20 for moving the column 4 in the left-right direction is provided on the upper surface of the moving plate 16. The X-axis direction moving mechanism 20 includes two rails 21 extending left and right, an X-axis screw shaft 22, an X-axis motor 23 (see FIG. 2), and a bearing 24.

  The rails 21 are provided at the front and rear of the upper surface of the movable plate 16, respectively. The X-axis screw shaft 22 extends left and right, and is provided between the two rails 21. Bearings 24 are provided at the left end and the middle of the X-axis screw shaft 22, respectively. The description of the bearing provided in the middle of the X-axis screw shaft 22 is omitted. The X-axis motor 23 is connected to the rear end of the X-axis screw shaft 22.

  A nut (not shown) is screwed to the X-axis screw shaft 22 via a rolling element (not shown). Grease is applied to the X-axis screw shaft 22. A plurality of sliders 26 are slidably provided on each rail 21. The column 4 is connected to the upper part of the nut and the slider 26. The column 4 has a columnar shape. The X-axis screw shaft 22 is rotated by the rotation of the X-axis motor 23, the nut moves in the left-right direction, and the column 4 moves in the left-right direction.

  A Z-axis direction moving mechanism 30 for moving the spindle head 5 in the vertical direction is provided on the front surface of the column 4. The Z-axis direction moving mechanism 30 includes two rails 31 extending vertically, a Z-axis screw shaft 32, a Z-axis motor 33, and a bearing 34.

  The rails 31 are provided on the left and right sides of the front surface of the column 4. The Z-axis screw shaft 32 extends vertically and is provided between the two rails 31. A bearing 34 is provided at each of the lower end and the middle of the Z-axis screw shaft 32. The illustration of the bearing provided in the middle part is omitted. The Z-axis motor 33 is connected to the upper end of the Z-axis screw shaft 32.

  A nut (not shown) is screwed to the Z-axis screw shaft 32 via a rolling element (not shown). Grease is applied to the Z-axis screw shaft 32. A plurality of sliders 35 are slidably provided on each rail 31. The spindle head 5 is connected to the nut and the front part of the slider 35. The rotation of the Z-axis motor 33 causes the Z-axis screw shaft 32 to rotate, the nut to move up and down, and the spindle head 5 to move up and down. The Z-axis motor 33, the Z-axis screw shaft 32, the nut and the rolling elements constitute a ball screw mechanism.

  A vertically extending spindle 5 a is provided in the spindle head 5. The main shaft 5a rotates around the axis. A spindle motor 6 is provided at the upper end of the spindle head 5. A tool is mounted on the lower end of the main shaft 5a. The rotation of the spindle motor 6 rotates the spindle 5a, and the tool rotates. The rotated tool processes the work held by the work holding unit 3.

  The machine tool 100 includes a tool changing device (not shown) for changing a tool. The tool changing device exchanges a tool housed in a tool magazine (not shown) and a tool mounted on the spindle 5a.

FIG. 2 is a block diagram schematically illustrating the configuration of the control device 50. The control device 50 includes a CPU 51, a storage unit 52, a RAM 53, and an input / output interface 54. The storage unit 52 is a rewritable memory, such as an EPROM or an EEPROM. Intersection table storage unit 52 to be described later, the path number i, the command point P _k, intersection S _i ^d, k final number of path A, path B, the first reference point O _m, and the second reference point L _m or the like Store (d, i, k, and m are natural numbers).

  When the operator operates the operation unit 7, a signal is input from the operation unit 7 to the input / output interface 54. The operation unit 7 is, for example, a keyboard, a button, a touch panel, or the like. The input / output interface 54 outputs a signal to the display unit 8. The display unit 8 displays characters, figures, symbols, and the like. The display unit 8 is, for example, a liquid crystal display panel.

  The control device 50 includes an X-axis control circuit 55 corresponding to the X-axis motor 23, a servo amplifier 55a, and a differentiator 23b. The X-axis motor 23 includes an encoder 23a. The X-axis control circuit 55 outputs a command indicating a current amount to the servo amplifier 55a based on a command from the CPU 51. The servo amplifier 55a receives the command and outputs a drive current to the X-axis motor 23.

  The encoder 23a outputs a position feedback signal to the X-axis control circuit 55. The X-axis control circuit 55 executes position feedback control based on the position feedback signal.

  The encoder 23a outputs a position feedback signal to the differentiator 23b, and the differentiator 23b converts the position feedback signal into a speed feedback signal and outputs the signal to the X-axis control circuit 55. The X-axis control circuit 55 executes speed feedback control based on the speed feedback signal.

  The current detector 55b detects the value of the drive current output from the servo amplifier 55a. The current detector 55b feeds back the value of the drive current to the X-axis control circuit 55. The X-axis control circuit 55 executes current control based on the value of the drive current.

  The control device 50 includes a Y-axis control circuit 56 corresponding to the Y-axis motor 13, a servo amplifier 56a, and a differentiator 13b. The Y-axis motor 13 includes an encoder 13a. The Y-axis control circuit 56 outputs a command indicating a current amount to the servo amplifier 56a based on a command from the CPU 51. The servo amplifier 56a receives the command and outputs a drive current to the Y-axis motor 13.

  The encoder 13a outputs a position feedback signal to the Y-axis control circuit 56. The Y-axis control circuit 56 executes position feedback control based on the position feedback signal.

  The encoder 13a outputs a position feedback signal to the differentiator 13b, and the differentiator 13b converts the position feedback signal into a speed feedback signal and outputs the signal to the Y-axis control circuit 56. The Y-axis control circuit 56 performs speed feedback control based on the speed feedback signal.

  The current detector 56b detects the value of the drive current output from the servo amplifier 56a. The current detector 56b feeds back the value of the drive current to the Y-axis control circuit 56. The Y-axis control circuit 56 performs current control based on the value of the drive current.

  The control device 50 includes a Z-axis control circuit 57 corresponding to the Z-axis motor 33, a servo amplifier 57a, and a differentiator 33b. The Z-axis motor 33 includes an encoder 33a. The Z-axis control circuit 57 outputs a command indicating a current amount to the servo amplifier 57a based on a command from the CPU 51. The servo amplifier 57a receives the command and outputs a drive current to the Z-axis motor 33.

  The encoder 33a outputs a position feedback signal to the Z-axis control circuit 57. The Z-axis control circuit 57 executes position feedback control based on the position feedback signal.

  The encoder 33a outputs a position feedback signal to the differentiator 33b, and the differentiator 33b converts the position feedback signal into a velocity feedback signal and outputs the signal to the Z-axis control circuit 57. The Z-axis control circuit 57 executes speed feedback control based on the speed feedback signal.

  The current detector 57b detects the value of the drive current output from the servo amplifier 57a. The current detector 57b feeds back the value of the drive current to the Z-axis control circuit 57. The Z-axis control circuit 57 executes current control based on the value of the drive current.

  The control device 50 also performs the same feedback control on the spindle motor 6 as the X to Z axis motors 23, 13, and 33.

  The machine tool 100 includes a magazine motor 60 and a magazine control circuit 58. The rotation of the magazine motor 60 drives the tool magazine. The magazine control circuit 58 controls the rotation of the magazine motor 60.

The storage unit 52 stores a machining program for machining a work. The machining program has a plurality of command points _Pk that indicate the position of the spindle 5a. k indicates the order of instructions constituting the machining program. The spindle 5a sequentially moves a plurality of command points _Pk , and the tool mounted on the spindle 5a processes a workpiece.

The storage unit 52 stores the command point _Pk in advance. The control device 50 sets a path (machining path) along which the spindle 5a moves based on the plurality of command points _Pk . The control device 50 executes the movement of the spindle 5a based on the machining path.

  A method for setting a machining path will be described. FIG. 3 is a plan view schematically showing a processing path and an evaluation cross section for the work, and FIG. 4 is a perspective view schematically showing an evaluation cross section for the work. In the drawings, the X direction indicates the left-right direction, the Y direction indicates the front-back direction, and the Z direction indicates the up-down direction. The shape of the workpiece in FIGS. 3 and 4 shows the shape after processing.

The control device 50 sets an evaluation section D ^d (d indicates a section number and is a natural number) for the workpiece. For example, as shown in FIG. 3, when the main shaft 5a moves spirally, the machining path is a path along the spiral direction. As shown in FIG. 3, the controller 50 sets a plurality of evaluation section D ^d along a direction substantially perpendicular to the machining path. The plurality of evaluation sections are arranged in the circumferential direction of the machining path. The operator instructs in advance that the direction of the machining path is the circumferential direction.

  The control device 50 executes a processing path setting process. FIG. 5 is a flowchart illustrating a processing path setting process performed by the control device 50.

  The CPU 51 of the control device 50 waits until a start signal is input (step S1: NO). For example, the user operates the operation unit 7 to input a start signal to the control device.

  If a start signal has been input (step S1: YES), the CPU 51 executes the outermost / innermost calculation processing (step S2), executes the evaluation section setting processing (step S3), and sets the command point position. A correction process is performed (Step S4). The details of the outermost / innermost calculation processing, the evaluation section setting processing, and the command point position correction processing will be described later.

  The outermost / innermost calculation processing will be described. FIG. 6 is a flowchart for explaining the outermost / innermost calculation processing. FIG. 7 is a schematic diagram schematically showing a machining path of the main shaft 5a moving from the outer peripheral side to the inner peripheral side in a spiral shape. FIG. 4 is a schematic view schematically showing a machining path of a main shaft 5a moving from an inner peripheral side to an outer peripheral side in a dashed manner.

CPU51, for a plurality of command point P _k, command point (start command point) located at the starting point of the machining path command point located at the end of the machining path from P ₁ (end point instruction point) order identifier to P _N (number) Is set (step S11).

CPU51 calculates the line segment P _a P _{a + 1} closest to the starting point command point P ₁ (step S12), and calculates the nearest line segment P _b P _{b + 1} to the end point command points P _N (step S13) .

CPU51 sets the machining path between the start command point P ₁ and the command point P _a to the route A (step S14), and the machining path between the endpoints command point P _N and the command point P _b on the path B It is set (step S15).

As shown in FIG. 7, when the main shaft 5a moves from the outer peripheral side to the inner peripheral side, the path A is located on the outermost side, and the path B is located on the innermost side. As shown in FIG. 8, when the main shaft 5a moves from the inner peripheral side to the outer peripheral side, the path A is located at the innermost position, and the path B is located at the outermost position. The route A and the route B each have a substantially annular shape. The ring shape includes a spiral shape as shown in FIG. Nearest segment P _a P _{a + 1} of the operation line segment P ₂ P ₃ from the start point command point P _1, P ₃ P _4, and calculates the shortest distance to ..., progressively from the maximum value of the outermost short Calculate the line segment of the minimum distance when it becomes smaller. Calculation of the nearest line segment P _b P _{b + 1} is the same.

CPU51 has the minimum value A _{x_min} and the maximum value A _{X_max} the X direction of the path A, and calculates the minimum value A _{Y_min} and the maximum value A _{Y_max} the Y direction (step S16).

CPU51 is the minimum value B _{x_min} and the maximum value B _{X_max} in the X direction of the path B, and calculating the minimum value B _{Y_min} and the maximum value B _{Y_max} the Y direction (step S17).

The CPU 51 determines whether or not A _{X_min} <B _{X_min} <B _{X_max} <A _{X_max} and A _{Y_min} <B _{Y_min} <B _{Y_max} <A _{Y_max} (step S18). If A _{X_min} <B _{X_min} <B _{X_max} <A _{X_max} and A _{Y_min} <B _{Y_min} <B _{Y_max} <A _{Y_max} (step S18: YES), the CPU 51 determines the route A to be the outermost route located at the outermost position. The route B is determined to be the innermost route located at the innermost position (step S19, see FIG. 7), and the process returns to the evaluation section setting process (step S3, see FIG. 5).

If A _{X_min} <B _{X_min} <B _{X_max} <A _{X_max} and A _{Y_min} <B _{Y_min} <B _{Y_max} <A _{Y_max} (step S18: NO), the CPU 51 determines that B _{X_min} <A _{X_min} <A _{X_max} <B _{X_max} and _{BY_min} < It is determined whether or not A _{Y_min} <A _{Y_max} <B _{Y_max} (step S20).

If _{BX_min} < _{AX_min} < _{AX_max} < _{BX_max} and _{BY_min} < _{AY_min} < _{AY_max} < _{BY_max} (step S20: YES), the CPU 51 determines the route A as the innermost route located at the innermost position. Then, the route B is determined to be the route located at the outermost position (step S21, see FIG. 8), and the process returns to the evaluation section setting process (step S3, see FIG. 5). One of the routes A and B constitutes a first route portion, and the other constitutes a second route portion.

If _{BX_min} < _{AX_min} < _{AX_max} < _{BX_max} and _{BY_min} < _{AY_min} < _{AY_max} < _{BY_max} (step S20: NO), the CPU 51 _reports an error (step S22) and ends the process. For example, the display unit 8 displays that an error has occurred in the outermost / innermost arithmetic processing.

After the error notification, if the operator adjusts or changes the data, such as setting the command value P _k again, and inputs the start signal to the control device 50 again, the CPU 51 performs the outermost / innermost calculation. You may comprise so that a process may be performed again.

  Next, the evaluation section setting processing will be described. FIG. 9 is a flowchart illustrating the evaluation section setting process, and FIG. 10 is a schematic diagram illustrating the evaluation section setting process.

The CPU 51 sets a plurality of first reference points O _m (m is a natural number) equidistantly separated from each other on the outermost route (step S31), and sets a plurality of second reference points L _m on the innermost route. (Step S32). Incidentally, the first reference point O _m is set at equal intervals from the start command point P ₁ in order. The setting of the second reference point will be described later.

The CPU 51 sets a point on the innermost route that is closest to the first reference point O _m as the second reference point L _m . CPU51 on the basis of the first reference point O _m and the second reference point L _m, and calculates the evaluation section D ^d, is set (step S33). CPU51, as a first reference point O _m and the second reference point L _m is located on the evaluation section D ^d, and calculates an evaluation section D ^d. The CPU 51 returns the process to the command point position correction process (Step S4, see FIG. 5). Calculation of the evaluation section D ^d is a plane perpendicular to the X-Y plane, and calculates a plane including the first reference point O _m and the second reference point L _m.

The second reference point L _m, because it is closest to the first reference point O _m, evaluation section D ^d becomes substantially perpendicular to the innermost path and outermost path (machining path).

FIG. 11 is a schematic diagram schematically showing a command point _Pk and an intersection of an evaluation section ^Dd and a machining path, and FIG. 12 is a conceptual diagram showing an example of an intersection table. 11 and 12, "i" (i is a natural number) indicates a path number in the orbital movement of the main shaft 5a. As shown in FIG. 11, for example, the route with the route number 1 (i = 1) indicates the outermost route, and the route with the route number 2 (i = 2) is a ring-shaped route located inside the route with the route number 1. Indicates a route. The same applies to route numbers 3 and below. The main shaft 5a moves in the order of the path numbers.

As shown in FIG. 12, the control device 50, each evaluation section D ^d, calculates the intersection S _i ^d the movement path P _k -P _k + _1, channel number i, the intersection coordinates S _i ^d and the movement path P _k -P _{k + 1} are associated and stored in the intersection table.

Controller 50 corrects the intersection position on the evaluation section D ^d for example, the first correction method. Figure 13 is an explanatory diagram for explaining a first method of correcting the intersection position on the evaluation section D ^d. The control device 50 corrects, for example, the coordinate in the Z direction gradually. To the intersection coordinates S _i ^d to be modified, the intersection coordinates s _i-2 ^d of the two points before and ^{_{after, s i-1 d, s}} i + 1 d, s i + 2 by using the ^d fixes t Determine _i ^d .

The Z coordinate values of the four intersection coordinates s _i-2 ^d , s _i-1 ^d , s _{i + 1} ^d , and s _{i + 2} ^d are represented by z _i-2 , z _i-1 , z _{i + 1} , z _{i +2} , the Z coordinate value of the correction point t _i ^d is z _i ′, and the difference between the Z coordinate values is d ₁ = z _i−2 −z _i−1 , d ₂ = z _i−1 −z _{i ′} , Assuming that d ₃ = z _i ′ −z _{i + 1} , d ₄ = z _{i + 1} −z _{i + 2,} and two differences d ₁₂ ′, d ₂₃ ′, and d ₃₄ ′ of Z coordinate values (difference of Z coordinate values) z _i ′ is calculated such that the difference (d ₁ , d ₂ , d ₃ , d ₄ ) changes linearly.

The twice differences d ₁₂ ′, d ₂₃ ′, and d ₃₄ ′ of the Z coordinate values are obtained by the following equations.
_{d 12 '= d 2 -d 1} = (z i-1 -z i') - (z i-2 -z i-1) = 2z i-1 -z i '-z i-2 ··· ( 1)
_{d 23 '= d 3 -d 2} = (z i' -z i + 1) - (z i-1 -z i ') = 2z i' -z i + 1 -z i-1 ··· (2 )
_{d 34 '= d 4 -d 3} = (z i + 1 -z i + 2) - (z i' -z i + 1) = 2z i + 1 -z i + 2 -z i ' ・ ・ (3)

Because these change linearly,
_{d 23 '= (d 12'} + d 34 ') / 2 ··· (4)
Meet.

Solving z _i ′ based on equations (1) to (4) gives
z _i ′ = (− z _i−2 + 4z _i−1 + 4z _{i + 1} −z _{i + 2} ) / 6
Becomes

Performing the modification for all intersections S _i ^d on evaluation section D ^d. It should be noted that only the intersections whose Z coordinate values are far apart from the Z coordinate values of other intersections may be corrected.

Controller 50 corrects the intersection position on the evaluation section D ^d for example in the second correction method. FIG. 14 is an explanatory diagram illustrating a second method of correcting the intersection point on the evaluation section. In FIG. 14, u corresponds to the XY coordinates, and v corresponds to the Z coordinates. The controller 50, for example using other multiple intersections surrounding the intersection S _i ^d to be corrected of the subject, to create a smooth curve (spline curves, Bezier curves, NURBS curve, etc.), the curved line At the intersection S _i ^d to be corrected.

When four intersections s _i-2 ^d , s _i-1 ^d , s _{i + 1} ^d , and s _{i + 2} ^d are used as a smooth curve, the section s _i-2 on the evaluation section D ^d (uv plane) is used. curve expressions v ₁ (u), v ₂ (u), ^d −s _i−1 ^d , intervals s _i−1 ^d −s _{i + 1} ^d , and intervals s _{i + 1} ^d −s _{i + 2} ^d , v ₃ (u) is given by the following equation.
v _j (u) = a _j (u-u _j ) ³ + b _j (u-u _j ) ² + c _j (u-u _j ) + d _j
(J = 1, 2, 3)

Based on the fact that the first and second derivatives at the intersections s _i-2 ^d , s _i-1 ^d , s _{i + 1} ^d , s _{i + 2} ^d and at the boundary points are continuous, 50 can determine a _{j to} d _j .

Selection of the four intersection points as described above, not limited to the case of using a continuous two points located on both sides of the intersection S _i ^d. For example, the intersection may be discontinuously selected every two points, such as intersections s _i-3 ^d , s _i-1 ^d , s _{i + 1} ^d , and s _{i + 3} ^d .

As shown in FIG. 14, fixes t _i ^d position, on a smooth curve, the distance from the intersection S _i ^d to be modified is a position where the minimum.

The corrected intersection group S ^d existing on the d-th evaluation section D ^{d is} defined as T ^d .
T ^d = {t _i ^d | d: section number, i: path number}

The controller 50 corrects the position of the command point by using the intersection group as ^Td . FIG. 15 is an explanatory diagram illustrating a method of correcting a command point. In Figure 15, P _a ~P _f indicates a command point.

For example, when the command point _Pc is a correction target, as shown in FIG. 15A, the command point _Pc is located between the section ^Dd-1 and the section ^Dd , and the path number is i. The control device 50 acquires the cross-sectional position and the path number for the command point _Pc with reference to the intersection table described above.

As shown in FIG. 15B, the intersection control device 50 surrounding the command point P _c, for example, four intersection points aligned on the machining path ^{_{t i d + 1, t i}} d, t i d-1, t i d- Explore ² The controller 50 creates four intersections ^{_{t i d + 1, t i}} d, t i d-1, t i smooth curve from ^d-2 (spline curves, Bezier curves, NURBS curve, etc.), curved line projecting the command point P _c in, to determine the correction point P _c '. The control device 50 obtains a smooth curve by a method similar to the above-described second correction method. The position of the correction point P _c ′ is a position on the smooth curve where the distance from the command point P _c is minimum. The control device 50 similarly corrects the positions of the other command points.

FIG. 16 is a flowchart illustrating the command point position correction processing. CPU51 is above evaluation section setting process (step S3, see FIG. 5) at, after setting the rated cross-section D ^d, creating an intersection table (see FIGS. 11 and 12). Specifically, the CPU 51 sets “1” to a variable i indicating the path number of the reciprocating operation and a variable k indicating the order of instructions constituting the machining program (step S41).

Then, the CPU 51 reads the movement route P _k -P _{k + 1} (step S42). CPU51 determines whether the moving path P _k -P _{k + 1} intersects the evaluation section D ^d (step S43). When the movement route P _k -P _{k + 1} does not intersect with the evaluation section D ^d (step S43: NO), the CPU 51 increments k by one (step S47).

If the moving path P _k -P _{k + 1} intersects the evaluation section D ^d (Step S43: YES), CPU 51 may evaluate sectional D ^d and the movement path P _k intersection between -P _{k + 1} S _i ^d is already It is determined whether or not it exists (step S44).

If the intersection point S _i ^d between the evaluation section D ^d and the movement path P _k -P _{k + 1} does not already exist (step S44: NO), CPU 51 is the intersection table in the storage unit 52 (see FIG. 12), the path number i, in association with the intersection coordinates S _i ^d and the moving path P _k -P _{k + 1} (step S46).

If the intersection point S _i ^d between the evaluation section D ^d and the movement path P _k -P _{k + 1} already exists (Step S44: YES), CPU51 is incremented by one to i (step S45), CPU 51 is stored the intersection table parts 52, path number i, the intersection coordinates S _i ^d and the moving path P _k -P _{k + 1} the correspondence stored (step S46), and one increments k (step S47). Steps S41 to S47 constitute an arithmetic unit.

  After incrementing k, the CPU 51 determines whether k is the final number (step S48). If k is not the final number (step S48: NO), the CPU 51 returns the process to step S42. When k is the last number (step S48: YES), the CPU 51 corrects the position of the intersection as described above (step S49, see equations (1) to (4), and FIGS. 13 and 14).

  As described above, the CPU 51 searches for an intersection around the command point (step S50), and corrects the position of the command point (step S51, see FIGS. 15A and 15B).

  In the embodiment described above, the route A and the route B are located at the outermost circumference and the innermost circumference, but are not limited thereto. One of the route A and the route B may be located on the outer peripheral side, and the other may be located on the inner peripheral side.

In the control unit 50 and the machine tool 100 according to the embodiment, and sets an evaluation section D ^d to be perpendicular to the annular machining path, the intersecting point S _i ^d evaluation section D ^d and machining path position fix, based on the position of the modified intersection S _i ^d, it corrects the position of the command point P _k in the direction crossing the machining path.

When a plurality of evaluation sections D ^d are set so as to extend radially from the center of the processing path with respect to the annular processing path, a high density portion and a low density portion of the evaluation cross section D ^d occur, and the command point P Correction accuracy for _k may decrease. In the above-described embodiment, by making the evaluation section D ^d perpendicular to the machining path, even if a difference occurs in the density of the evaluation section D ^d , it is possible to prevent a decrease in correction accuracy for the command point P _k . be able to.

In addition, a first reference point O _m and a second reference point L _m are set for the outer peripheral path and the inner peripheral path (path A and path B), respectively. The second reference point L _m is closest to the first reference point O _m. As the first reference point O _m and the second reference point L _m is located on the evaluation section D ^d, by setting the evaluation section D ^d, evaluation section D ^d is substantially perpendicular to the machining path.

When the distance between the outer peripheral path and the inner peripheral path is small, the set evaluation section D ^d is inclined with respect to the machining path due to a slight calculation error or the like and intersects with the other evaluation sections D ^d . Sometimes. In the embodiment, since the outer peripheral path is located on the outermost peripheral side and the inner peripheral path is located on the innermost peripheral side, there is sufficient space between the outer peripheral path and the inner peripheral path. , A large distance can be provided to prevent the evaluation cross sections from intersecting with each other.

  One of the outer peripheral path and the inner peripheral path is located on the starting point side of the machining path, and the other is located on the end point side of the machining path. When the starting point is located at the center of the spiral machining path, the outer peripheral path is located at the end point side, and the inner peripheral path is located at the starting point side. When the end point is located at the center of the machining path, the inner peripheral path is located at the end point side, and the outer peripheral path is located at the start point side.

5a Spindle 50 Controller 51 CPU
52 storage unit 53 RAM
100 machine tool

Claims (7)

In a control device that sets a machining path based on a plurality of command points that indicate the position of the spindle and controls movement of the spindle based on the machining path,
The machining path has to multiple path portion, such a ring,
An evaluation section setting unit that sets a plurality of evaluation sections so as to be perpendicular to each of the plurality of path units ,
A computing unit that computes a plurality of intersections between each evaluation section and each path set by the evaluation section setting unit;
Intersection position correction unit that corrects the positions of the plurality of intersection points calculated by the calculation unit without performing processing of the workpiece and measurement of the actual shape of the processed workpiece ,
Based on a plurality of intersections which are fixed in intersection point position correcting unit, and a command point position correcting unit for correcting the position of the instruction point in a direction intersecting the machining path,
The intersection position correction unit determines the position of the first intersection to be corrected, a plurality of second intersections that are present on the evaluation cross section where the first intersection is present and are around the first intersection. and corrected using,
The command point position correction unit is arranged along the same path as the predetermined path, based on the plurality of intersections aligned along the predetermined path and corrected by the intersection position correction. A control device for correcting the positions of the plurality of command points existing on a plurality of evaluation sections . The plurality of path units include:
An annular first path portion;
A second path portion that is located inside the first path portion and forms an annular shape;
The evaluation section setting unit includes:
A first reference point setting unit that sets a first reference point on the first path unit;
A second reference point setting unit that sets a second reference point at a position closest to the first reference point on the second path unit;
The control device according to claim 1, further comprising: an evaluation section calculation unit configured to calculate the evaluation section based on the first reference point and the second reference point. In front SL multiple path portion, the first path portion is located outermost,
The control device according to claim 2, wherein the second path portion is located at an innermost position among the plurality of path portions. The processing path is spiral,
The plurality of command points include a start point command point located at a start point of the machining path and an end point command point located at an end point of the machining path,
A start-point-side path portion setting section that sets one of the first path portion or the second path portion between the start point command point and the first command point different from the start point command point;
An end point side path section setting section that sets the other of the first path section or the second path section between the end point command point and a second command point different from the end point command point. The control device according to claim 2 or 3, wherein A control device according to any one of claims 1 to 4,
A machine tool comprising: the spindle. In a control method for setting a machining path based on a plurality of command points indicating the position of the spindle and controlling the movement of the spindle based on the machining path,
The machining path has to multiple path portion, such a ring,
A plurality of evaluation sections are set to be perpendicular to each of the plurality of path portions ,
A plurality of intersection between each evaluation section and the respective route section set computed,
Correcting the calculated positions of the plurality of intersections without performing processing of the workpiece and measuring the actual shape of the processed workpiece ,
Based on the modified plurality of intersection points, to correct the position of the instruction point in a direction intersecting the machining path,
The position of the first intersection point is Osamu positive subject, and corrected using a plurality of second intersection surrounding the present and the first intersection point on evaluation section the intersection of the first is present,
Positions of the plurality of command points aligned along the same route as the predetermined route and present on the plurality of evaluation cross sections based on the plurality of intersections aligned and corrected along the predetermined route; A control method characterized by correcting the following. A computer program executable by a control device that controls a movement of the spindle based on the machining program, sets a machining path based on a plurality of command points that indicate the position of the spindle, and controls the movement of the spindle based on the machining path.
The machining path has to multiple path portion, such a ring,
The control device,
An evaluation section setting unit that sets a plurality of evaluation sections to be perpendicular to each of the plurality of path sections;
A computing unit that computes a plurality of intersections between each evaluation section and each path set by the evaluation section setting unit;
Without performing processing and measurement of the actual shape of the processed workpiece of the workpiece, a plurality of the arithmetic unit is modified by the intersection position correcting section, and intersection point position correcting unit for correcting the position of said plurality of intersections calculated Based on the intersection of the, to function as a command point position correction unit that corrects the position of the command point in the direction intersecting the machining path,
The intersection position correction unit determines the position of the first intersection to be corrected, a plurality of second intersections that are present on the evaluation cross section where the first intersection is present and are around the first intersection. and corrected using,
The command point position correction unit is arranged along the same path as the predetermined path, based on the plurality of intersections aligned along the predetermined path and corrected by the intersection position correction. A computer program for correcting the positions of the plurality of command points existing on a plurality of evaluation sections .

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